Precision depth guided instruments for use in vertebroplasty

Abstract

Precision depth guided instruments are provided for use in performing percutaneous implantation of hard tissue implant materials. A depth guided stylet include a point adapted for piercing hard tissue, and preferably, self-tapping threads for self-tapping into hard tissue. The stylet may include an elongated rod having a first section having a first diameter, and a second section having a second diameter larger than the first diameter. A cannula for use with a depth guided stylet includes an elongated tube having first and second open ends adapted for a depth guided stylet to pass therethrough. The cannula may include a pawl passing through the elongated tube for ratcheting against a rack of gear teeth provided on the stylet. Alternatively, a camming mechanism may be pivotal arranged on the stylet. Upon pivoting the camming mechanism, the cam surface provides a driving force against the cannula to drive the cannula along the stylet. A method of using the instruments is also disclosed, as is a kit which includes the instruments and which is used to open a pathway into hard tissue.

What is claimed is: 
     
       1. A stylet, comprising: an elongated rod having first and second ends and a longitudinal axis, said first end terminating in a point adapted for piercing hard tissue; and   a camming mechanism pivotally mounted to provide a driving force to a cannula upon pivoting said camming mechanism with respect to said elongated rod.   
     
     
       2. The stylet of claim 1, further comprising a handle attached to said second end of said elongated rod. 
     
     
       3. The stylet of claim 1, further comprising: self-tapping threads extending from said point along said elongated rod for a predetermined distance, said self-tapping threads adapted to self-tap into hard tissue.   
     
     
       4. A kit adapted to open a pathway into hard tissue, comprising: a depth guided stylet comprising: an elongated rod having first and second ends and a longitudinal axis, said first end terminating in a point adapted for piercing hard tissue; and   a camming mechanism pivotally mounted to provide a driving force to a cannula upon pivoting said camming mechanism with respect to said elongated rod; and     a cannula comprising: an elongated tube having first and second ends, said first and second ends being open and adapted for said depth guided stylet to pass therethrough; and   a surface adapted to interact with said camming mechanism for the transfer of said driving force.     
     
     
       5. The kit of claim 4, further comprising: self-tapping threads extending from said point along said elongated rod for a predetermined distance, said self-tapping threads adapted to self-tap into hard tissue.   
     
     
       6. The kit of claim 4, wherein said depth guided stylet further comprises a handle provided on said second end for providing a mechanical advantage to a user in rotating said elongated rod about said longitudinal axis. 
     
     
       7. The kit of claim 4, wherein said cannula further comprises a handle provided on said second end of said elongated tube, said surface being located on said handle of said cannula. 
     
     
       8. The kit of claim 7, further comprising a connector on said handle for connecting said cannula to tubing following removal of said stylet from within said cannula. 
     
     
       9. The kit of claim 8, wherein said connector comprise a Luer lock fitting. 
     
     
       10. The kit of claim 8, further comprising a bore through at least a portion of said handle, said bore connecting said connector with said elongated tube. 
     
     
       11. The kit of claim 10, wherein a longitudinal axis of said bore is non-parallel with and intersects a longitudinal axis of said elongated tube. 
     
     
       12. The kit of claim 4, wherein said elongated tube comprises a first section having a first diameter, and a second section having a second diameter larger than said first diameter; and wherein said first section is closer than said second section to said first end of said elongated tube.   
     
     
       13. The kit of claim 12, wherein said elongated rod comprises a first rod section having a first rod diameter, and a second rod section having a second rod diameter larger than said first rod diameter. 
     
     
       14. A stylet, comprising: an elongated rod having first and second ends and a longitudinal axis, said first end terminating in a point adapted for piercing hard tissue;   threads extending from said point along said elongated rod for a predetermined distance; and   means for biasing said elongated rod with respect to a cannula, in a direction of said longitudinal axis, said means for biasing being movable from a first position, at which said elongated rod extends from an end of the cannula to allow said threads to engage tissue; and a second position, at which said cannula covers substantially all of said threads.   
     
     
       15. A kit adapted to open a pathway into hard tissue, comprising: a depth guided stylet comprising: an elongated rod having first and second ends and a longitudinal axis, said first end terminating in a point adapted for piercing hard tissue; and     threads extending from said point along said elongated rod for a predetermined distance;   a cannula comprising: an elongated tube having first and second ends, said first and second ends being open and adapted for said elongated rod to pass therethrough; and     means for biasing said cannula, in a direction of said longitudinal axis, with respect to said stylet, said means for biasing being movable from a first position, at which said elongated rod extends from an end of the cannula to allow said threads to engage tissue; and a second position, at which said cannula covers substantially all of said threads.